There’s more than a few climate bloggers who have a dirty little secret. We like to excoriate those who can’t tell the difference between weather and climate, or herald every momentary drop in temperature as evidence that global warming has ended, or revel in each new report that suggests not every single square millimeter of the planet’s surface is experiencing dramatic climate shifts. As we should. But many of us take a peek, every morning, at the daily version of a graph from the National Snow and Ice Data Center depicting current sea-ice extent in the Arctic.

We know that what happens from day to day tells us nothing useful about global climate change. We know that the only things that supply meaningful information are measured on the scale of decades and even centuries, not days, weeks or months. And yet we still obsess on that damn graph. Why?
I’ll tell you why. Because what happens with the Arctic ice cover is critical to projecting the future of the whole Earth ecosystem. Because the changes that have been observed up there are so dramatic. And because we’re human. Even the head of the NSIDC, Mark Serreze, admits to getting caught up in the incredible unfolding story of melting ice. After sea-ice extent dropped waaaay below the 30-year norm in 2007, words from the experts like “death spiral” led some amateurs more excitable types to predict the entire summer ice cap could gone by 2013.

“In retrospect, the reactions to the 2007 melt were overstated. The lesson is that we must be more careful in not reading too much into one event,” Serreze said.

Of course, reading too much into one season’s ice cover trends is a mistake. But so is using language like “flatlining,” to describe the situation at the moment, as one prominent pseudoskeptic writes. The graph at right may or may not lend itself to that interpretation, depending on when you’re reading this. I am linking directly to the URL that provides a new graph every day.

But given the stakes, it really isn’t that surprising that so much attention is paid to every wobble in the trends. A new paper in Geology goes a long way to explaining why. “Signiﬁcantly warmer Arctic surface temperatures during the Pliocene indicated by multiple independent proxies” says the Arctic was a heck of lot warmer than previously thought during a period of time a few million years ago when carbon-dioxide level were comparable to today’s (390 parts per million). We’re talking somewhere around 19 °C, not just 4 or 5 degrees, warmer. That’s 34 Fahrenheit.

While it is true that many things were different 3 or 4 million years ago, during the Pliocene. CO2 levels are just one of them. But CO2 levels are a primary contributor to the global temperature, and the paper’s results cannot be ignored.

The Canadian, Dutch and American authors of the paper used three proxies to determine local temperatures in the high latitudes — “fossil tetraether lipids” in fossil bacteria (the precise makeup molecules of fat that are sensitive to temperature), oxygen isotope rations in trees, and ancient vegetation diversity. They did this because the standard ice-core data only go back a million years. While it is possible the one or two of the chosen proxies could have built-in biases in the same direction, it is extremely unlikely that all three would be similarly problematic. It turns out that the proxies all produced remarkably similar results:

This more robust temperature estimate suggests that Arctic temperatures were remarkably warmer during the Pliocene. In fact, these estimates are 5-10 °C warmer than previous proxy estimates. These temperature estimates are also consider-ably warmer than model simulations at high latitudes. However, climates at high latitude are known to be very sen-sitive to orbital parameters affecting insolation, and thus proxy estimates with uncertain age constraints are not directly comparable to model simulations that typically span hundreds of years. Nonetheless, the agreement among these estimates indicates signiﬁcant Arctic warming during the Pliocene.

What’s really interesting is not just how much warmer the Arctic was back then than other analyses had assumed, but exactly what part of the thermometer is involved. Instead of the Arctic being -25 to -15 °C or so, it was close to 0 °C. Which means we’re now in the zone where melting is much more easy.

And if the Arctic sea ice melts, the resulting loss of albedo (reflectivity) of the north polar region drops by something like 80 or 90%. The Arctic ocean starts warming, and so does the air above it. The entire region gets a lot warmer. The ice on Greenland starts to melt, too. Sea levels rise. The temperature gradient between the equator and the poles — a gradient that is largely responsible for every major weather pattern on the planet — is significantly weakened. In other words, lose the Arctic sea ice, and everything changes.

The paper’s authors wrap up with this note:

Our independent proxy estimates indicate that Arctic temperatures during the Pliocene were considerably warmer than previous estimates derived from empirical proxies and climate model simulations, despite estimates of Pliocene atmospheric CO2 levels that are comparable to today. This indicates that climate models do not incorporate the full array of atmospheric, biospheric, and cryospheric feed-back mechanisms necessary to simulate Arctic climate. Regardless of the feedback mechanism responsible for ampliﬁed Arctic temperatures, our results indicate that a signiﬁcant increase in Arctic temperatures may be imminent in response to current atmospheric CO2 levels.

And that’s the kind of thing that drive climate change bloggers to skip over the to sea ice extent graph. Yes, it’s kind of good to see the blue line stop plummeting and head over toward what passes for normal in the satellite record (which only goes back to 1979). But we’re not going to stop looking. And there’s another reason.Sea-ice extent isn’t nearly as important as sea-ice volume. And after several years of above-average melt, much of what’s left in the Arctic is thinner than it used to be, and could easily disappears. Some would argue we should be obsessing instead over this graph:

The problem with this graph is it’s generated from a computer model, not the satellite observations behind the ice extent graph. After all, it takes a lot more work to measure ice thickness than simply snapping a photo from orbit. But you can read about why the models are trusted here.

The northwest passage is not open at the present time, it was open for a brief period last summer, and the summer before, as it has been at other times in the past, the RCMP made the first recorded single year passage in 1944.

Will it open enough to allow anyone to navigate it this year? You can guess yes, or you can guess no, but there is no certainty in any prediction.

The heavy lift vessels Beluga Fraternity and Beluga Foresight did commence an East-to-West passage of the Northern Sea Route in August 2009.[7][9] However they were part of a small convoy escorted by the Russian nuclear icebreaker 50 Years Since Victory, westward through the Bering, Sannikov and Vilkizki Straits. The two, new (2008) ice-strengthened heavy-lift vessels embarked Russian ice pilots for the voyage to the western Siberian port of Novyy, in the Yamburg region in the delta of the Ob River. The ships arrived Novvy on 7 September, discharged their cargo to barges and departed on the 12th, bound for the Kara Gates and Rotterdam.
In completing this journey, they were the first commercial vessels from the Western World to do so.[10] The captain of the Beluga Foresight, Valeriy Durov, described the achievement as “great news for our industry”.[10]

Adolf Erik Nordenskiöld and Northeast Passage commemorative coin
The company president of Beluga Shipping claimed the voyage saved each vessel about 300,000 euros, compared to the normal Korea-to-Rotterdam route by way of the Suez Canal. The company did not disclose how much they paid for the escort service and the Russian pilots. An 18 September 2009 press release stated that the company is already planning for six vessels to make Arctic delivieries in 2010.[11]

We provide an analysis of Greenland temperature records to compare the current (1995–2005) warming period with the previous (1920–1930) Greenland warming. We find that the current Greenland warming is not unprecedented in recent Greenland history. Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.

RE: #9 —Note that Chylek et al’s 2006 paper stepped back from their assertion of Greenland’s cooling in their earlier 2004 paper.

Why is this germane?

“Short time periods are always more variable.”

Yes, so true. But how ‘short’ is short, and when is a ‘trend’ really a trend? There are no rules, but there are lots of judgments. Not to mention the fact that every hot day in the summer is touted as further proof of …But perhaps, you don’t make such silly errors.

My basic point is that the record is very variable. The trends, such as they are, are small and easily ‘adjusted’ one way or another by assumptions made in statistical processing. Confirmation bias aka ‘cherry picking’ is a tremendous danger to all. The fact that today’s ‘events’ are not unprecedented proves nothing of course, but it does lend a lot of plausibility to a skeptical point of view. Once again, I must quote a geologist friend of mine who said, when I asked him about this controversy ten years ago or more, “Too little data, too much uncertainty…”

“when is a ‘trend’ really a trend? There are no rules, but there are lots of judgments.”

Actually, there is a rule, based on the heat capacity of the world’s oceans. They act as “thermal shock absorbers” to soak up heat when the globe warms and release heat when the globe cools. The rate at which they do so depends on the temperature differential, of course, but we can calculate a rough estimate of how long a temperature excursion must be before we can conclude that the excursion constitutes a trend rather than a fluctuation. That time period is roughly 30 years. In other words, climatic changes that are shorter than 30 years in duration can be dismissed as fluctuations; only changes that persist for longer than 30 years can be considered a trend. And as you can see from the graph above, the trend has been continuing for at least 30 years now. In contrast, the example you cite cover 10-year periods, and so are of little relevance to long-term trends.

Your definition of trend sound reasonable, but I don’t know if it is generally accepted. Trends are perceptions of data, and are always time/scale dependent.

Regarding the 30-year graph, the blogger notes that it is derived from computer models, not observations, although the models are ‘trusted.’

I also note that the overall trend over thirty years is -3,400 sq km per decade. Have I read that somewhat fuzzy graphic correctly? And the total arctic extent is something around 12 million sq km, depending on who’s counting? If this is a trend, is it a significant trend? If it persists for a few decades and then … stops…will any harm be done? What does it really tell us? Don’t start in on converging streams of observation, now…

BTW, the blogger refers to “pseudoskeptics.” WHAT is that? Someone who supports AGW but pretends not to?

Lichanos, the 30-year figure is indeed so “rule-of-thumb” that it is never used in formal analyses; however, the underlying concept is universally accepted. The problem is that, to be rigorous, the amount of time you consider to be minimal to establish a trend depends on how large a change you consider significant. The 30-year figure I use is based on a change in global temperature of 1ºC, IIRC.

You’re also right about the figure used above; however, it refers to sea ice VOLUME, not area, so you’re comparing apples and oranges. A more useful source is IPCC AR4 WG1 Figure 4.9, which shows the trend in summer minimum arctic sea ice extent from 1979 to 2005. The linear trend is -60 ± 20 x 10**3 km**2 yr**-1, or approximately 7.4% per decade. This graph clearly shows that we are indeed facing serious loss of arctic sea ice in the 21st century.

I can only guess what somebody else means by “pseudoskeptics”, but I take it to mean people who call themselves skeptics but in fact are extremely gullible regarding arguments against the AGW hypothesis.

This kind of fits with the question I’ve had about climate change: How do we know when we’re really (techincal term) hosed? Am I correct that a summer free of Arctic sea ice would be a one strong indicator at least?

bcoppola, I don’t think that there will ever be a day when we can say, “Today, we’re hosed.” That’s a black-and-white, catastrophe-or-just-fine way of thinking about the problem. A better way is to think in terms of how much climate change will cost us in dollar terms. Obviously, any such number is a wild guess, but they’ve been working on it, and we can be certain that we’re already in for costs in the trillions of dollars even if we reduce CO2 emissions right now. The more CO2 we dump, the higher the net cost. If we really go hog-wild with CO2 emissions, we’re talking about troubles that could ultimately drag us into a world war, in which case, the figure goes way, way up.

Thanks for pointing out my careless reading of the chart. Yes, volume. I thought it said km2, but probably, if I could read it, it would say km3.

7.4% would be a significant trend, but I have noted a lot of controversy about how to estimate sea ice volume each year. I remain unconvinced by modeled ‘observations.’

BTW, your correction removes a nagging doubt I had – Why the heck would they model the observation of what is visible from a satellite? Of course, ice thickness is not so easily observed, thus the models. Thanks again!

Regarding costs, your arguments carry little conviction since you could make the opposite argument on cost. Of course, nobody wants to say, “It’s cheaper to fight a war,” although that is what we do every ten years it seems, when we fight in the Middle East (cheaper than reducing our dependence on their oil, that is.) But really, the same argument could be applied to language, money, the steam engine, etc. If only we hadn’t invented and used those things, WWII, WWI, the Civil War, etc. etc. wouldn’t have happened.

What about the death and endlessly predicted, and quite probable wars over scarce water? Only we civil engineers fret about that – nobody else seems to be mobilizing for world solutions to the problem. It’s happening now. Ditto malaria, AIDS, etc.

To put it simply, the probablities of horrible human self-destructiveness are always high and are massively over-determined.

Yes, the cost estimates are highly uncertain. This should not deter us from making a decision; after all, nobody has ever worked out the precise cost of a thermonuclear war, but I think we can all agree that it would be unacceptably high. All the rough guesstimates that I have seen come out to cost numbers much greater than the cost of policies such as a carbon tax. Yes, it’s possible to come up with a carbon tax so high that it would be economically ruinous, but the realistic scenarios with carbon taxes under $100/ton show substantial reductions in CO2 emissions with costs running into the hundreds of billions, not trillions. (This is assuming that any such carbon tax is revenue-neutral: it is offset by reductions in other taxes.)

…nobody has ever worked out the precise cost of a thermonuclear war, but I think we can all agree that it would be unacceptably high.

If we had based our policy decisions on a cost-benefit analysis, I am pretty sure we would have had WWIII. I am just old enough to have clear memories of the Cold War, and some of the looney ‘intellectuals’ that provided policy ‘guidance’ for it. That only goes to show how idiotic an approach it is to questions of this nature.

I guess I should specify what I meant by “hosed”: The point where no practical reduction in CO2 output will avert civilization-threatening effects such as massive droughts, sea level rise that swamps populated coastal areas worldwide, populated semi-arid ares (like, say, much of Mexico and the US Southwest) becoming uninhabitable, and the loss or serious depletion of major glacier-fed rivers like the Yellow and Ganges. Or worse, a point where climate change becomes a runaway feedback cycle (as I’ve heard is possible) regardless of CO2 output reductions. Wasn’t thinking at all about mere economic costs.

I’m more optimistic about cost-benefit analysis than you are, Lichanos. I agree that, done badly, it can lead to bad results — but ANY form of reasoning done badly will do that. Done properly, cost-benefit analysis is often a superior means of decision-making. Certainly we would have been much better off if Mr. Bush had used some cost-benefit analysis before attacking Iraq.

bcoppola, I don’t share your disdain for economic analysis — it’s the best way, I think, to consolidate all sorts of different considerations. How do we weigh the loss of the Maldive Islands against job losses here in the USA? Do we just declare that Americans are more important that Maldiveans? The only way we can pull together all sorts of disparate effects is by reducing them to economic costs and toting them all up. Sure, it’s not very soulful, but it sure beats the gut hunch approach.

…done badly, it can lead to bad results — but ANY form of reasoning done badly will do that.

So true. That’s exactly why I have so little confidence in the pronouncements of the IPCC and it’s fans.

BTW, my point about the inutility of cost-benefit analysis is based on the observation that people are quite happy to get to the analysis part before they have resolved the basic questions of how to value anything, and what to value. Unfortunately, that takes a lot of thought, and a minimum of calculation. Everything that comes afterwards is just accounting. Sure the process is a good one, especially if you are comparing alternatives for keeping your house warm, or fixing an electrical system. Very simple stuff, that…

Lichanos, again we disagree on a subjective matter: in this case, how reliable the IPCC analysis is. I’ve read the whole thing and closely examined a few of its details, and I find the reasoning quite solid. Yes, there are a few cases of hand-waving, but they do not impact the overall conclusions. Certainly none of the criticisms I have read seem to have any substance to them.

I also don’t think that it’s that difficult to determine a valuation for most things: simply ask the affected people about alternatives that they’d be willing to accept and determine the costs of those alternatives. For example, let’s take the hypothetical case I suggested: comparing the loss of the Maldives (not likely anytime soon, of course) with job losses in the USA. For the Maldives, we offer the residents several options: relocation to a new home (all expenses paid) that’s snazzy enough to attract their interest, or perhaps provision of the billions of tons of rock and sand necessary to raise the elevation of the islands by a meter or two. We can come up with good cost estimates for both of these options; obviously, they’d run into the hundreds of billions or trillions of dollars.

Meanwhile, we already have some pretty good numbers for the economic costs of job losses. At the simplest, we could pay for make-work schemes that would compensate for lost jobs. That too would cost a lot of money. But we could compare the two figures and weight them by their relative connections through AGW to determine which course is less expensive.

I know this sounds terribly crass, but it really is possible to put a price on most things. Just ask people what they’d want to compensate and you have a valuation. Getting an honest answer might be difficult, of course — you need to plan the system to insure honest answers. But it’s conceivable in most cases.

Lichanos, again we disagree on a subjective matter: in this case, how reliable the IPCC analysis is.

Ah, so at least we agree that we are disagreeing about a subjective matter. On that basis, interesting discussion and argument can proceed.

I have never dismissed AGW as fraudulent or absurd. I admit that it is a plausible hypothesis worth pursuing. Because of the complexity of the issue, the evidence, the system, and even of the definition of the problem, not to mention the fact that most of the ‘proof’ is of statistical nature, human judgment of the case is absolutely required. (Feynman wrote that judgment is ALWAYS required in science, i.e., it is to some degree always subjective. One must ‘weigh’ the evidence in most cases.)

So, it’s not an open-shut case. Not ‘basic science, duh!’ This is the skeptic position – we remain unconvinced for a host of reasons. Mann et al. – this blogger too – would have it that we reject science. Absurd.

Lichanos, I have no quarrel with somebody who honestly assesses the evidence and decides that it does not have enough weight to support policy actions. However, I have yet to encounter honest arguments to this effect; the arguments advanced by denialists — at least, all those that I have come across — are contrived or overstated. Add to this the strong political bias — all denialists I have encountered are politically conservative whereas not all supporters of AGW are politically liberal — and I conclude that there just isn’t any honest case against AGW. I won’t reject the possibility that your own personal case against it is honest; I don’t know what your case is.

By the way, there’s a problem with this statement of yours:

most of the ‘proof’ is of statistical nature

There’s no such thing as proof in science (as your subsequent clause indicates). There’s only evidence supporting and opposing. You weigh the evidence and go with the preponderance of evidence. If you’re expecting proof, then your expectations are unrealistic. Moreover, there’s absolutely nothing wrong with statistical evidence; as one scientist said more than a century ago, the logic of the world is the calculus of probabilities. At the most fundamental level, ALL scientific knowledge is statistical in nature. To dismiss evidence that is statistical is to dismiss the evidentiary process itself.

I agree that it’s not an open-and-shut case. But the case is so strong, so compelling, that it is not at all absurd to characterize denialists as rejecters of the scientific mentality.

Just yesterday, I was at my veterinarian’s office, where I noticed a map showing incidence of heartworm disease in dogs in the different counties in my state. There were some serious oddities in the map: counties adjacent to each other, with similar environments and population densities, showed dramatically differing incidences of heartworm disease. I discussed the oddities with the vet, who admitted that there was no good explanation for the anomalies. I would expect that a logically consistent denialist would conclude from this data that there is no need to medicate their dogs against heartworms. After all, the science is still subject to uncertainties, and the medication against heartworms is a bit expensive. However, that’s not how I think. I’d rather not take chances with my dogs’ health: I spend the money for the heartworm medication because my vet advises me to do so, and I trust his judgement, and the evidence I have seen backs up his advice. I consider this a prudent policy. You, apparently, do not. If you do consider it a prudent policy on my part, what’s the difference between the two issues (heartworms and AGW)?

However, I have yet to encounter honest arguments to this effect…
You cannot have looked very hard.

the arguments advanced by denialists — at least, all those that I have come across — are contrived or overstated. Add to this the strong political bias — all denialists I have encountered are politically conservative
Why don’t you stay away from the ‘denialists’ and just seek out opinions of scientists who don’t have a public axe to grind, but who may have serious doubts about the AGW hypothesis. If you are relying on those you class as denialists, you’ve pretty much limited your sample pool right off.

And yes, a lot of public skeptics are conservatives or libertarians. I am certainly not, but those are the breaks. The ones I read generally keep their politics separate, so I don’t have to pay attention to it.

To dismiss evidence that is statistical is to dismiss the evidentiary process itself.
I did not dismiss it. My point is that the magnitude of the trends is small, so they are inconclusive and subject to nudging and biasing very easily. Saying that ALL scientific evidence is statistical is like saying that ALL art is abstract art because it is all an abstraction from perception. In fact, I say this often to make a point, but that doesn’t stop me from putting Mondrian and Rafael in totally different stylistic groups. Similarly, you can argue that all evidence is statistical, but there are degrees of everything…

If you do consider it a prudent policy on my part, what’s the difference between the two issues (heartworms and AGW)?
Are you actually serious about this question? Heartworms are organisms – we see them in dog stool samples. The distribution of the condition may not be clearly explained, but the etiology of it is. Arguments like this make me think that AGW people are simply religious fundamentalists in disguise.

“However, I have yet to encounter honest arguments to this effect…
You cannot have looked very hard.”

I’ve spent plenty of time reading WUWT, Spencer, Climate Audit, and a few lesser denialist blogs. I’ve even gone through some of Monkton’s stuff. I really do want to see what these people are saying. And, as I wrote earlier, I find their arguments contrived or overstated.

Why don’t you stay away from the ‘denialists’ and just seek out opinions of scientists who don’t have a public axe to grind, but who may have serious doubts about the AGW hypothesis.

First, I’m not sure what constitutes “having a public axe to grind”. Does that mean “disagrees with you”? If we get into motivations, we have all sorts of issues with funding for denialists. More important, when a body as august as the NAS weighs in on the matter, I think we can dismiss the issue of “having a public axe to grind”.

And who are those scientists who have serious doubts about AGW? I’ll grant there’s Lindzen and a handful of others. But Lindzen’s arguments aren’t compelling — where’s he’s believable, there isn’t much import, and where his arguments have import, they aren’t believable. There are some scientists who advance seriously flawed arguments — Soon leaps to mind. There are plenty of cranks, too, who advance truly idiotic arguments. And there are always the geologists who point out (correctly) that the earth has been warmer before — but fail to note that civilization wasn’t around during those times and, if those conditions were replicated today, civilization would be clobbered.

I just haven’t seen any remotely convincing arguments against the basic AGW hypothesis. Sure, there are plenty of disputable fine points, but nothing fatal to the hypothesis. I suppose I’ll have to ask you to delve into details here and list what you consider to be the strongest arguments against the basic AGW hypothesis.

My point is that the magnitude of the trends is small, so they are inconclusive and subject to nudging and biasing very easily.

I disagree. You may think that an average temperature change of 1ºC is small, but it can have very large effects. Indeed, we are already seeing significant changes in ecosystems arising from the small changes in temperature that have already occurred. For example, pine borers are already wreaking a lot of damage to forests in the American northwest and Canada because winters aren’t cold enough to kill off the larvae. That’s billions of dollars of damages that we are ALREADY suffering due to AGW. Agriculture in California is facing reductions in water supplies because the Sierra snowpack is melting earlier each year. Higher temperatures in the American Great Plains require greater amounts of irrigation, even as the supplies of underground water are being depleted. The list of effects goes on and on, and they are already adding up to billions of dollars. Sure, a temperature increase of 1ºC won’t force you to unbutton your shirt, but it can still have a lot of expensive consequences.

Saying that ALL scientific evidence is statistical is like saying that ALL art is abstract art…

I don’t know anything about art, but I do know something about science, and science without data is kinda pointless. You gotta have data to do science, and data normally takes quantitative form — and no measurement exists without some uncertainty to it. Thus, it really is true that statistics dominates all scientific thinking. Even fields that lack much quantitative basis still end up relying on statistics for solid results. Let’s take hominid paleontology, for example. It’s pretty hard to do statistics on the handful of fossils that we’ve dug up. But in fact, the non-statistical work in hominid paleontology doesn’t carry much weight — paleontologists have learned how to apply statistical techniques to even the fragmentary data they’ve collected. And with each passing year, they put more and more emphasis on the statistical methods, such as pollen counts, flake analysis, and so forth. Even psychologists have come up with all sorts of clever schemes for approaching problems from a statistical point of view; the experiments that analyze the amount of time that infants’ eyes are directed toward an object as an indicator of infant thought processes are particularly revealing in this regard.

Are you actually serious about this question? Heartworms are organisms – we see them in dog stool samples. The distribution of the condition may not be clearly explained, but the etiology of it is. Arguments like this make me think that AGW people are simply religious fundamentalists in disguise.

Perhaps you misunderstand my point. Remember, the purpose of heartworm medication is not to treat a condition after it arises, but to prevent it arising in the first place. I don’t wait for stool samples to demonstrate the presence of heartworms — by then it’s much too late. I use the medication (Heartgard) in the belief that it will prevent heartworms from infecting my dogs. Thus, I am spending money to prevent a problem whose threat is based solely on probabilities derived from scientific analysis. Conceptually, this is exactly the same problem that we face with AGW. Although we already have evidence of damage arising from AGW, our real concern lies in future developments predicted by scientific analysis — just like my dogs. Are we willing to spend money based only on scientific analysis rather than direct evidence of actual damage taking place right now? In the case of my dogs, I am willing to do that. And in the case of AGW, I use exactly the same reasoning to come to the same conclusion. I would expect that, if you were consistent, your refusal to accept sacrifices now to ward off AGW would be mirrored by a refusal to medicate your (hypothetical) dogs against heartworms.

Arguments like this make me think that AGW people are simply religious fundamentalists in disguise.

I’m a stone cold rationalist. I follow the logic where ever it takes me, even if I find the results unpalatable. That’s why I support policy actions to ward off AGW.

The reason I follow blog threads like this is because I am interested in the logic of argument. You have provided me with lots of material. I will not go into the details of specific data sets that you request because that would take much more space than a comment. I will only make this points about the logic of your position – after all, science requires both induction and deduction to progress:

And there are always the geologists who point out (correctly) that the earth has been warmer before — but fail to note that civilization wasn’t around during those times and, if those conditions were replicated today, civilization would be clobbered.
Glad you recognize that bona fide scientists in this field are among the most doubtful of AGW. I think your argument is typical of AGW proponents in several ways. You correctly note one objection sometimes raised by geologists, and you correctly observe that civilization wasn’t around in those epochs. Why does that matter? What has that to do with the point that the geologists are making? Isn’t their point that the earth’s temperature has varied in the past and that human action isn’t necessarily the cause? You immediately bring in the specter of us being ‘clobbered’ as if that clinches the argument. It’s just a scare tactic.

I disagree. You may think that an average temperature change of 1ºC is small, but it can have very large effects.
Again, you are answering an objection that is irrelevant or non-existent. I know that 1 degree C can be significant in some ecosystems, and five or six would certainly bring changes of significance that might be disruptive to humans as well. THAT’S NOT MY POINT. The MAGNITUDE of the changes is still small on the scale of temperature. The fact that it may be important doesn’t make it bigger or any less susceptible to bias or nudging due to its small size on the Kelvin scale. FIRST decide if the small change is REAL, then decide what impacts it would have.

I use the medication (Heartgard) in the belief that it will prevent heartworms from infecting my dogs. Thus, I am spending money to prevent a problem whose threat is based solely on probabilities derived from scientific analysis. Conceptually, this is exactly the same problem that we face with AGW.
You use Heartgard because you know that it will prevent heartworm, and you know that dogs get heartworm more or less easily. It’s a pretty simple chain of causation, and it’s a very simple remedy. You have vastly less certainty, with a far more disruptive and uncertain remedy for AGW. They are nowhere near comparable, although the structure of the argument is, I grant you.

Interesting. You ignore empirical differences in favor of deductive logic when it suits you, and you use faulty syllogisms propped up by fearful induction when it suits you. That’s why I am not convinced.

I can certainly respect your preference not to get into the scientific details — those arguments have already been carried out better than either your or I can do. However, those scientific arguments are in fact the meat of this controversy, and skipping them confines our discussion to little more than secondary points.

Glad you recognize that bona fide scientists in this field are among the most doubtful of AGW.

While the geologists are certainly bona fide scientists, I don’t consider them to be bona fide in the field of climatology, which this is all about. There’s a fine point worthy of careful consideration here. Geologists have rightly observed that the earth has been warm before. But the existence of past warm periods does not in the slightest way argue against the possibility that anthropogenic emissions of CO2 are responsible for the current warming. The fact that forest fires in past times were often caused by lightning strikes (and still are) does not mean that humans can’t cause forest fires.

Moreover, geologists have nothing to say about the rate of temperature change; their field does not have the temporal resolution to decide just how quickly the earth warmed in times past. Although we have evidence of rapid cooling events in the past, there is scanty evidence for any temperature rise as rapid as the current one in times past. Thus, the geological evidence has no value to us in evaluating the potential threat of anthropogenic releases of CO2.

Isn’t their point that the earth’s temperature has varied in the past and that human action isn’t necessarily the cause?

Of course human action isn’t NECESSARILY the cause. There could be a million possible causes — in science you can’t be so narrow-minded as to think that there could only be one cause for any phenomenon. But you can accumulate evidence and theory that strongly indicates the most likely cause, and that is what has been done with AGW theory. You can also accumulate evidence that rejects alternate hypotheses. In the case of AGW, geology provides no alternate hypothesis that cannot be rejected with current evidence. For example, geology can demonstrate that certain catastrophic events, such as collisions with asteroids, can have profound effects upon climate. However, as yet, geologists have failed to produce any evidence that an asteroid struck the earth in the last 50 years. So we can reject that hypothesis.

I remind you that it’s not robust logic to attempt to discredit a hypothesis with the observation that “some unknown force might be at work”. If you can identify that force, and gather evidence as to its effects, then you’ve got a case. But merely saying, as geologists do, that similar climatological symptoms have been observed in the past does not in any way speak against the hypothesis that the currently observed symptoms are caused by anthropogenic releases of CO2.

You immediately bring in the specter of us being ‘clobbered’ as if that clinches the argument. It’s just a scare tactic.

I was addressing the historical scenarios that geology describes, in which sea levels were up to 100 feet higher than today. I didn’t come up with that number, geologists did. I’m not predicting that outcome in the foreseeable future. I’m arguing that, if you want to embrace the geologist’s suggestion that the current warming is merely a repetition of past occurrences, then you have to conclude that we’re really screwed — which I don’t believe. Observing that past conditions would be catastrophic if they existed today is not a scare tactic — it’s a valid point. I don’t believe that the past conditions that geologists point to are in any way relevant to this issue. Neither should you.

The MAGNITUDE of the changes is still small on the scale of temperature. The fact that it may be important doesn’t make it bigger or any less susceptible to bias or nudging due to its small size on the Kelvin scale.

I misunderstood your point; I assumed too optimistically. Your point that the absolute value of the change is too small to be logically significant is without foundation. That’s the whole reason we use statistical analysis: it tells us how reliable our numbers are. You seem to have a prejudice against statistical analysis. To that, all I can say is, statistics is fundamental to scientific analysis; if you truly do reject the application of statistical analysis to scientific methodology, then you truly are rejecting science.

And the results of the statistics are very clear. We can do a simple linear fit to the temperature measurements over the last hundred years to show that the increases in temperatures are statistically significant to better than 1% reliability.

It’s true that the application of statistical analysis, at its finer points, can get quite esoteric. But esoteric doesn’t mean “wrong” — it means that you need some expertise to understand the logic. There are indeed a number of fine points that arise from the statistical analyses of the climatological data — but none of these are serious enough to call into question the overall results.

Again, you seem to think that, as soon as we bring statistics into the analysis, all sorts of skullduggery becomes possible. That simply isn’t true. The amount of complex statistical analysis that has been carried out by scientists in the last 40 years is truly staggering, and along the way, science has learned a great deal about what works and what doesn’t. The great majority of the statistical methods used in AGW theory are tried and true and beyond question. Indeed, “Mike’s trick” to “hide the decline” was one such statistical technique that Mr. Mann published in Nature for other scientists to critique, and it seems to have gained acceptance as a reliable method.

So yes, the change, however small in absolute magnitude, is absolutely real.

You use Heartgard because you know that it will prevent heartworm, and you know that dogs get heartworm more or less easily. It’s a pretty simple chain of causation, and it’s a very simple remedy. You have vastly less certainty, with a far more disruptive and uncertain remedy for AGW. They are nowhere near comparable, although the structure of the argument is, I grant you.

Yes, my point was about the structure of the arguments: In both cases I have to consider spending money to ward off a potential problem. In neither case do I have solid assurances that the money I spend provides protection commensurate with the expenditure. In both cases, I must rely upon the advice of an expert, even though I can understand the problem at a simple level. You maintain that the two situations are nowhere near comparable, because 1) the causal chain is clearer in the heartworm case; and 2) the expenditure is smaller in the heartworm case.

I disagree with both of your arguments. The causal chain in the heartworm case includes completely unknowable steps, such as the probability that one of my dogs will be bitten by a mosquito. My dogs never stray from our land, and there are no standing pools of water anywhere near my land, so the probability of mosquitos biting them SEEMS small — but can I be certain? I’m gambling on a straight probabilistic guess, whereas in the case of AGW, we’re not facing a probability that temperatures might or might not increase. We already know that temperatures have increased, and we are certain that they will continue to increase. The only uncertainties concern the magnitude and rate of increase, and we are gathering more data every year that helps us zero in on these numbers. But I have no prospect of ever gaining further data regarding the likelihood of mosquito bites.

Second, you are comparing the cost of Heartgard with the cost of warding off temperature rises. A more useful comparison is the cost-benefit ratio of the two strategies. IIRC, Heartgard costs me $10/month/dog. I don’t know what the cost of after-infection treatment would be, but I have to balance the overall cost of Heartgard ($120/year) against the probability of infection and the cost of after-infection treatment. Is the cost/benefit ratio lower than 1.0? That might be a tricky calculation.

By contrast, we have lots of evidence suggesting that the cost-benefit ratio for reducing climate change is very low. We know that climate change is already costing us billions per year, and all indications are that the bill will soon climb to trillions per year. Weigh this against the economic consequences of a carbon tax; it’s pretty hard to imagine a carbon tax high enough to cost the world economy trillions of dollars.

It is certainly true that the costs of climate change mitigation are present costs and the benefits are in the future; here we have to come up with an appropriate discount rate. I suspect that most denialists are unconsciously using high discount rates (i.e., “Screw the kids!”) I myself prefer a discount rate in the neighborhood of 4% or 5%, which is the historical norm for the last century or so.

By the way, this leads us to the most correct formulation of the policy issue: will posterity be better off with high temperatures and an economy that has grown faster, or with lower temperatures and an economy that has grown more slowly? But this question is of no interest to people who don’t give a damn about posterity and just want to enjoy their SUVs today. And I concede that, if you don’t care about posterity, then there’s no case for taking action to mitigate climate change.

Again, you seem to think that, as soon as we bring statistics into the analysis, all sorts of skullduggery becomes possible. That simply isn’t true.

Not true that it is possible? Are you kidding? I’m not saying it’s inevitable, but possible? How can you deny it?

I worked for many years in a firm that created computer models of large natural water systems, bays, estuaries, parts of the ocean. I saw firsthand how difficult it is to calibrate models with scarce data, what has to be done to produce usable time-series input. I attended many meetings with GISS as part of my job and listened to them explain their analytical approaches. I have spent a lot of time reading the analyses of the statistics at the heart of the AGW debate and its controversies. Your statement:

We can do a simple linear fit to the temperature measurements over the last hundred years to show that the increases in temperatures are statistically significant to better than 1% reliability.

strikes me a nothing less than amazingly credulous. There it is, my judgment against yours. Talk to you in fifteen years – my guess is people will be scratching their head wondering how we could have put so much faith in those models.

Not true that it is possible? Are you kidding? I’m not saying it’s inevitable, but possible? How can you deny it?

I can deny it when there’s plenty of oversight. Sure, it’s possible for a handful of dastards working in the dark to fudge the data, but the whole scientific method is built around the knowledge that you can’t trust individuals. That’s why there’s this huge system of intellectual auditing: you have to get the right degree, then you have to get a position at a research institution, then you have to get funding, then you have to write your paper, then it has to be scrutinized by several referees, and then it has to be scrutinized by the community at large. Just getting a paper published doesn’t get you there — somebody could come out of the woodwork and blow your paper to hell.

With all these eyeballs looking over your shoulder, it’s really hard to get away with skullduggery. Possible? I suppose so. But feasible? I don’t think so. There are just too many independent audits.

Which brings me to “The Killer Argument”, the argument that no denier has ever been able to respond to. 140 years ago Congress, realizing that it was having difficulty figuring out which scientific advice was reliable and which wasn’t, decided to create an advisory society. They wrote up a detailed charter that specified how this scientific society was to operate, provided it with generous funding, and imposed one absolute requirement: Your advice must be absolutely reliable. Thus was born the National Academy of Sciences. Only the elite of American science are invited to join, and being a member is a huge feather in your cap. Congress from time to time asks the NAS to report on some scientific matter of political interest, and the NAS is not required to give a simple yes or no answer. They are free to say “We don’t know” or “More research is required” — and in fact, they have done so many times. in particular 35 years ago when they were first asked about global warming and came back and said “Not enough data. More research needed. No opinion at this time.”

Their conservatism has been frustrating many times when they refuse to declare a scientific result that most scientists embrace, but it has proven effective: in 140 years, the NAS has never — NEVER — issued a report that later turned out to be incorrect or misleading. They have an absolutely perfect track record. And guess what? They have issued a number of reports on AGW; here’s a lead quote from one of their reports:

A strong, credible body of scientific evidence shows that climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems

So I put this question to you: do you really think that you’re smarter than the body of eminent scientists at the National Academy of Sciences?

You write:

Your statement:…strikes me a nothing less than amazingly credulous

No, my statement is scientifically informed. You may have listened to other people describing their analyses, but I have actually DONE lots of time-series analyses. I have done the statistics, and I’ve had to defend my work against the criticisms of scientists. I know how these things are done and I am acutely aware of the problems and criticisms. But I also know how to deal with those problems, and how to arrive at reliable analyses. That doesn’t mean that I can make uncertainty go away — but I know how to calculate the uncertainty.

You are welcome to your judgement, but I remind you, that judgement is contradicted by the judgement of a very large number of experts whose expertise in this matter vastly exceeds your own. Thus, I ask again: do you think that your judgement is superior to that of the collective judgement of the scientists at the National Academy of Sciences? No denialist has ever been able to answer that question. Can you?

I am not interested in skullduggery. I was too lazy to change the word. I have repeatedly stated that fraud is the least of my concerns. Bias, sloppiness, groupthink, that’s what concerns me.

You know absolutely nothing about my background, so you shouldn’t make assumptions about my expertise.

You may have done much analysis of time-series data, as have I, but that doesn’t mean yours are any good. Perhaps you make the same errors the AGW folks make. They are common enough.

So, you final argument comes to an appeal to authority. This, after recounting a rather idealistic view of how scientific progress is made. Yes, there are checks and reviews, but stupidity steal makes headway. The wonderful thing about science is that it can’t do so forever. Sometimes it is found out in a day, sometimes a year, sometimes many years. AGW is almost impossible to refute because it makes so few positive and falsifiable claims.

I put very little store in “collective judgment.” I’m not even sure what that means. I would welcome the chance to discuss the issue with the individual members of the NAS.

So, you final argument comes to an appeal to authority. This, after recounting a rather idealistic view of how scientific progress is made.

First, there’s no mismatch between the two ideas you mention. Second, there’s nothing wrong with an appeal to authority in this case. A lot of people labor under the mistaken impression that “appeal to authority” is poor reasoning. In fact, making recourse to authority is REQUIRED when dealing with matters requiring special expertise. If you’re an expert, then you can argue the evidence directly. But if you’re not an expert, then you simply don’t understand the evidence and you are wise to appeal to the authority of those who DO understand the evidence. Certainly it is foolhardy to reject the advice of experts when you don’t understand the material yourself. After all, that’s why Congress created the NAS in the first place: to get a reliable source of expert advice.

I put very little store in “collective judgment.” I’m not even sure what that means.

Actually, your position is a little different: you put more store in your own judgement than in the collective judgement of the scientists of the NAS. I won’t condemn you for that. But you’re in the same boat with the people who embrace homeopathy, the people who reject vaccination, and those who prefer intelligent design to evolution. Just like them, you reject the considered judgement of the experts and maintain that your own judgement is superior to theirs. That’s your right, of course, but I’m glad that antirationalists like you are still a minority. If our body politic embraced such hubris — well, you know what the Greeks said about hubris.

I think we have now clearly identified the matter that separates us. I am a rationalist — I follow the evidence and logic where-ever it takes me. You instead rely on a cognitive process that does not appear to be based on rational calculations — at least, you haven’t offered rational arguments supporting your judgement, other than the fact that you witnessed some people doing statistical analyses and you weren’t impressed with their work. That’s pretty thin gruel on which to base a general rejection of statistical methods.

It’s very difficult for us to have a meaningful discussion when you are basing your points on subjective matters for which there is no objective foundation. Such a discussion is merely a demolition derby of opinions. I’d be happy to move the discussion to a more productive theme by talking about objective evidence, the scientific ideas at play here. So far, you have avoided that area, but perhaps now that we have reduced our difference to an impasse, we could attempt a more constructive approach to the issue.

That’s pretty thin gruel on which to base a general rejection of statistical methods.

Amazing to me how consistently you fail to read my comments or insist that I said what you think I would say. I do not reject statistical methods. I am skeptical of their results in many cases, depending on the purveyor and the context.

OK, you are refining your position; that’s good. You are skeptical of statistical methods in many cases, depending on the purveyor and the context. So, do you have a logical standard that you apply in determining what statistics methods meet your approval and what statistical methods do not meet your approval? Can you articulate that logical standard?

Lance, it would appear that the patience you commend Lichanos for has been exhausted. His postings have grown shorter and more personal with time; I believe that he was running out of gas. Perhaps, however, he has been doing some research and will provide us with some substantiation for his claims. So far, we haven’t seen much in the way of evidence from him.